Dinitrosyldihalo complexes of molybdenum and tungsten are useful as components in catalyst systems. For example, a dinitrosyldihalo complex of molybdenum or tungsten, such as bis(triphenylphosphine)dinitrosyldichloromolybdenum, is a useful component in a catalyst system, such as a homogeneous catalyst system employing the molybdenum or tungsten catalyst component together with an aluminum-containing adjuvant such as methylaluminum sesquichloride, or the like, in a process of olefin disproportionation.
The molybdenum and tungsten complexes heretofore have been prepared by processes such as reacting molybdenum oxytetrachloride with NO and triphenylphosphine, or by reacting dichlorodinitrosylmolybdenum with triphenylphosphine. However, other methods employing more convenient reactants would be desirable, to provide a more useful and economical catalyst system ultimately for such olefin disproportionation reactions.